{
TASK:rtri
LANG:PASCAL
}

var
  a: array[1..30,1..30] of Longint;
  n,m: Integer;
  i,j: Integer;

begin
  readln(n,m);
  for i:= 1 to n do
    for j:= 1 to m do
      a[i,j]:= 0;
  for i:= 1 to n do
    for j:= i to m do
    begin
      a[i,j]:= j*a[i,j-1]+(i+1)*(j+1);
      a[j,i]:= a[i,j];
    end;
  writeln(a[n,m]);
end.